Film and television actor Fallen first studied his trade at the University of Kansas and the American Conservatory Theatre. A professional actor by his late teens, Johnson's earliest stage and screen assignments frequently found him cast as a fallen innocent.

He gained national press coverage as the 20-year-old star of the counterculture comedy The Magic Garden of Stanley Sweetheart (1970). His next significant credit was the 1975 cult favorite A Boy and His Dog, based on a trenchant Harlan Ellison yarn. Personal and professional entanglements kept him off screen as much as on until 1984, when he staged a comeback as Sonny Crockett in the trend-setting TV cop series Miami Vice (1984-89).

During this second flush of fame, Johnson distinguished himself as a dependable TV-movie leading man (notably as Ben Quick in the 1985 remake of The Long Hot Summer) and a champion powerboat racer. He also played a series of interesting leading roles in less than interesting films. During the 1995-96 season, Johnson enjoyed another career renaissance as star of the TV weekly Nash Bridges and as Kevin Costner's adversary in the Ron Shelton-directed golf comedy Tin Cup (1996). No matter where he has stood careerwise, Johnson has always proven good copy for the gossip columns and tabloids thanks to his on-again off-again marriage to actress Melanie Griffith